economic valuation of water regulation function by central alborz rangeland ecosystems

natural ecosystems provide many goods and services for human beings via their multiple functionalities. one of these important functions is the role of natural ecosystems in regulation of hydrologic cycle and increasing the infiltarion and retention of water in soil context and preventing from water runoff which may cause in unfavorable consequences like soil erosion and flooding. quantification and economic valuation of these functions is of high importance to regulate the utilization process from these resources. this research is trying to quantify and economically valuate the role of mid-taleghan rangelands as a representative ecosystem of central alborz region in water regulation and conservation function. curve number methodology was applied and effective data layers were overlaid to prepare cn map of the study area. supposing the lack of rangeland vegetation cover, its effects on hydrologic cycle and runoff and infiltration quantities were studied, followed by estimating economic value of the function using replacement cost method. results show the value of 960628 rials per acre as the average annual economic value of this function. the importance of this value is especially due to the location of the study area which covers the upper areas of taleghan reservoir dam and could be useful for water resources management and policy making.